System and method for controlling engine knock using electro-hydraulic valve actuation

STATEMENT OF GOVERNMENT RIGHTS

p-0002This invention was produced pursuant to United States Government Program No. DE-FC26-05NT42415 with the Department of Energy (DoE). The U.S. Government has certain rights in this invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

p-0003This application is related to U.S. Pat. No. 6,886,510 filed on Apr. 2, 2003. The disclosure of the above application is incorporated by reference in its entirety.

FIELD

p-0004The present disclosure relates to internal combustion engines and more particularly to a system and method for controlling engine knock using electro-hydraulic valve actuation (EHVA).

BACKGROUND

p-0005The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

p-0006Internal combustion engines draw air into an intake manifold through an inlet system that may be regulated by a throttle. The air in the intake manifold may be distributed to a plurality of cylinders through a plurality of intake valves, respectively, and combined with fuel to create an air/fuel (A/F) mixture. The A/F mixture may be combusted within the cylinders to drive pistons that rotatably turn a crankshaft generating drive torque. Exhaust gas resulting from combustion may be expelled from the cylinders through a plurality of exhaust valves, respectively, and into an exhaust manifold.

p-0007The intake and exhaust valves may be actuated by one or more camshafts. Alternatively, however, the intake and exhaust valves may be actuated using electrically controlled hydraulic actuators (“electro-hydraulic” control). The electro-hydraulic control of intake and exhaust valves of an engine may be referred to as electro-hydraulic valve actuation (EHVA). Therefore, an engine that incorporates EHVA may not include camshafts (i.e., a cam-less engine). For example, EHVA systems may selectively actuate (i.e., open) intake and exhaust valves by controlling hydraulic pressure (e.g., oil pressure).

SUMMARY

p-0008A control system for an engine includes a knock control module and a valve control module. The knock control module adjusts a period that one or more of an intake valve and an exhaust valve of a cylinder are open based on engine knock corresponding to the cylinder. The valve control module, based on the adjusted period, controls the one or more of the intake valve and the exhaust valve using one or more hydraulic actuators.

p-0009A method for controlling an engine includes adjusting a period that one or more of an intake valve and an exhaust valve of a cylinder are open based on engine knock corresponding to the cylinder, and based on the adjusted period, controlling the one or more of the intake valve and the exhaust valve using one or more hydraulic actuators.

p-0010In still other features, the systems and methods described above are implemented by a computer program executed by one or more processors. The computer program can reside on a tangible computer readable medium such as but not limited to memory, nonvolatile data storage, and/or other suitable tangible storage mediums.

p-0011Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

<figref idrefs="DRAWINGS">FIG. 1</figref> is a functional block diagram of an exemplary engine system according to the present disclosure;

<figref idrefs="DRAWINGS">FIG. 2</figref> is a schematic of an exemplary electro-hydraulic actuated valve according to the present disclosure;

<figref idrefs="DRAWINGS">FIG. 3</figref> is a functional block diagram of an exemplary control module according to the present disclosure; and

<figref idrefs="DRAWINGS">FIG. 4</figref> is a flow diagram of an exemplary method for controlling engine knock using electro-hydraulic valve actuation (EHVA) according to the present disclosure.

DETAILED DESCRIPTION

p-0017The following description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A or B or C), using a non-exclusive logical or. It should be understood that steps within a method may be executed in different order without altering the principles of the present disclosure.

p-0018As used herein, the term module refers to an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.

p-0019Abnormal combustion of an air/fuel (NF) mixture in an engine may cause engine knock (i.e., combustion noise, or vibration of the engine). Engine systems that control intake and exhaust valves using one or more camshafts may be limited in controlling engine knock. More specifically, camshaft engines may have a limited number of valve control profiles (e.g., two). Conventional control systems, therefore, may manage (i.e., limit) engine knock by adjusting spark advance. More specifically, conventional control systems may retard spark advance to decrease engine knock. Retarding spark advance, however, may result in decreased fuel economy.

p-0020Accordingly, a system and method are presented for improved control of engine knock using electro-hydraulic valve actuation (EHVA). The system and method may control a load of one or more cylinders when engine knock is detected. For example, the system and method may detect engine knock when a measurement by an engine knock sensor (i.e., engine knock intensity) is greater than a predetermined knock threshold. Decreasing engine knock by controlling the load of one or more cylinders allows for continued maximum brake torque (MBT) spark timing (i.e., no retarding of spark advance).

p-0021The system and method may decrease the load of the cylinder by decreasing a fresh air charge in the cylinder. For example, the system and method may decrease the fresh air charge by decreasing a period that the intake valve is open. Additionally or alternatively, the system and method may decrease the load of the cylinder by diluting the air in the cylinder. For example, the system and method may dilute the air in the cylinder by increasing a period that both the intake valve and the exhaust valve are open (“valve overlap”). Additionally, for example, the system and method may dilute the air in the cylinder by decreasing a period that the exhaust valve is open (i.e., close the exhaust valve earlier).

p-0022Referring now to <figref idrefs="DRAWINGS">FIG. 1</figref>, an engine system <b>10</b> includes an engine <b>12</b>. For example, the engine <b>12</b> may include a spark ignition (SI) engine, a compression ignition (CI) engine (e.g., a diesel engine), or a homogeneous charge compression ignition (HCCI) engine. The engine <b>12</b>, however, may also include a different type of engine and/or additional components, such as in a hybrid engine system (e.g., an electric motor, a battery system, a generator, etc.).

p-0023The engine <b>12</b> draws air into an intake manifold <b>14</b> through an intake system <b>16</b> that may be regulated by a throttle <b>18</b>. For example, the throttle <b>18</b> may be electrically controlled (e.g., electronic throttle control, or ETC). A mass air flow (MAF) sensor <b>20</b> may measure a rate of airflow into the intake manifold <b>14</b>. For example, the measurement of the MAF sensor <b>20</b> may indicate a load on the engine <b>12</b>. The air in the intake manifold <b>14</b> may be distributed to a plurality of cylinders <b>22</b> through a plurality of intake valves <b>24</b>, respectively. While six cylinders are shown, the engine <b>12</b> may include other numbers of cylinders.

p-0024The air may be combined with fuel from a plurality of fuel injectors <b>26</b> to create an air/fuel (A/F) mixture. For example, the fuel injectors <b>26</b> may inject the fuel via intake ports of the cylinders <b>22</b>, respectively (e.g., port fuel injection) or directly into the cylinders <b>22</b>, respectively (e.g., direct fuel injection). Additionally, for example, the fuel injectors <b>26</b> may inject the fuel at different times depending on the type of engine. The A/F mixture in the cylinders <b>22</b> may be compressed by pistons (not shown) and ignited by a plurality of spark plugs <b>28</b>, respectively (e.g., SI engines or HCCI engines using spark assist). The air in the cylinders <b>22</b>, however, may also be compressed by the pistons (not shown) and combusted by injecting the fuel into the pressurized air (e.g., CI engines, such as diesel engines).

p-0025The pistons (not shown) rotatably turn a crankshaft <b>34</b> generating drive torque. An engine speed sensor <b>36</b> may measure a rotational speed of the crankshaft <b>34</b> (e.g., in revolutions per minute, or RPM). The drive torque may be transferred to a driveline <b>38</b> (e.g., wheels) of the vehicle via a transmission <b>40</b>. Additionally, for example, the transmission <b>40</b> may be coupled to the crankshaft <b>34</b> via a fluid coupling such as a torque converter. A transmission output shaft speed (TOSS) sensor <b>42</b> may measure a rotational speed of an output shaft of the transmission <b>40</b> (e.g., in RPM). For example, the measurement of the TOSS sensor <b>42</b> may indicate a speed of the vehicle.

p-0026Exhaust gas resulting from combustion may be expelled from the cylinders <b>22</b> through a plurality of exhaust valves <b>30</b>, respectively, and into an exhaust manifold <b>44</b>. Specifically, the intake and exhaust valves <b>24</b>, <b>30</b> may be actuated by hydraulic actuators <b>32</b>. In other words, the hydraulic actuators <b>32</b> may be electrically controlled to selectively actuate (i.e., lift) the intake and exhaust valves <b>24</b>, <b>30</b>. The exhaust gas in the exhaust manifold <b>44</b> may then be treated by an exhaust treatment system <b>46</b> before being released into the atmosphere. The exhaust gas, however, may also be recycled, such as into the intake manifold <b>14</b> via an exhaust gas recirculation (EGR) system or to power a turbocharger (not shown). The engine <b>12</b>, however, may also include other types of forced induction (e.g., a supercharger).

p-0027An engine knock sensor <b>48</b> may measure engine knock. More specifically, the engine knock sensor <b>48</b> may measure vibration of the engine <b>12</b> (e.g., combustion noise). For example, the engine knock sensor <b>48</b> may be a digital knock sensor. Additionally, while a single engine knock sensor is shown, more than one engine knock sensor may be implemented. For example, the engine system <b>10</b> may include an engine knock sensor for each of the plurality of cylinders <b>22</b>. In other words, a plurality of engine knock sensors may be implemented for measuring engine knock of the plurality of cylinders <b>22</b>, respectively.

p-0028A control module <b>50</b> communicates with and controls various components of the engine system <b>10</b>. Specifically, the control module <b>50</b> may receive signals from the throttle <b>18</b>, the MAF sensor <b>20</b>, the fuel injectors <b>26</b>, the spark plugs <b>28</b>, the hydraulic actuators <b>32</b>, the engine speed sensor <b>36</b>, the transmission <b>40</b>, the TOSS sensor <b>42</b>, the exhaust treatment system <b>46</b>, and/or the engine knock sensor <b>48</b>. The control module <b>50</b> may control the throttle <b>18</b> (e.g., ETC), the intake and exhaust valves <b>24</b>, <b>30</b> (by controlling the hydraulic actuators <b>30</b>), the fuel injectors <b>26</b>, the spark plugs <b>28</b>, the transmission <b>40</b>, and/or the exhaust treatment system <b>46</b>. Additionally, the control module <b>50</b> may communicate with and/or control other components (e.g., an EGR system, a turbocharger or supercharger, etc.). The control module <b>50</b> may also implement the system or method of the present disclosure.

p-0029Referring now to <figref idrefs="DRAWINGS">FIG. 2</figref>, an exemplary electro-hydraulic actuated valve <b>55</b> is shown. For example, the electro-hydraulic actuated valve <b>55</b> may include one of the hydraulic actuators <b>34</b> and one of the intake or exhaust valves <b>26</b>, <b>32</b>. The electro-hydraulic actuated valve <b>55</b> includes a hydraulic actuator <b>60</b>, a valve <b>61</b>, and a return spring <b>62</b>. Specifically, the hydraulic actuator <b>60</b> is selectively energized by controlling hydraulic fluid pressure to open/close the valve <b>61</b>. The valve <b>61</b> may be locked by trapping the hydraulic fluid (i.e., maintaining a constant hydraulic pressure). The return spring <b>62</b> may assist the valve <b>61</b> in returning to a closed position (i.e., when the actuator <b>60</b> is de-energized).

p-0030The electro-hydraulic actuated valve <b>55</b> also includes first, second, and third solenoids <b>63</b>-<b>65</b>, respectively. For example, the first and second solenoids <b>63</b>, <b>64</b> may include two-way solenoids and the third solenoid <b>65</b> may include a three-way solenoid. The first, second, and third solenoids are electrically controlled (e.g., via the control module <b>50</b>) to control the hydraulic fluid pressure and thus control the hydraulic actuator <b>60</b> and the valve <b>61</b>. Additionally or alternatively, the electro-hydraulic actuated valve <b>55</b> may include an internal feedback system (IFS) <b>69</b> for controlling the hydraulic fluid flow/pressure and thus controlling the hydraulic actuator <b>60</b> and the valve <b>61</b>.

p-0031Specifically, the control module <b>50</b> may selectively actuate combinations of the first, second, and/or third solenoids <b>63</b>-<b>65</b> to allow hydraulic fluid flow (and thus hydraulic pressure) from first, second, and third hydraulic fluid rails <b>66</b>-<b>68</b>, respectively. For example, the first hydraulic fluid rail <b>66</b> may include a low pressure rail (e.g., less than a first threshold), the third hydraulic fluid rail <b>68</b> may include a high pressure rail (e.g., greater than a second threshold), and the second hydraulic fluid rail may include a mid-pressure (i.e., base pressure) rail (e.g., between the first and second thresholds, or rather a pressure between the low and high pressure rails).

p-0032Referring now to <figref idrefs="DRAWINGS">FIG. 3</figref>, the control module <b>50</b> is shown in more detail. The control module <b>50</b> may include a knock control module <b>74</b>, and a valve control module <b>78</b>. The control module <b>50</b> may also include memory (not shown) for storing determined and/or predetermined parameters. For example, the memory (not shown) may include non-volatile memory (NVM).

p-0033The knock control module <b>74</b> receives a signal from the engine knock sensor <b>48</b> (a “knock signal”). For example, the knock signal may indicate an intensity of the measured engine knock. The knock control module <b>74</b> may also receive signals indicating engine operating parameters. For example, the knock control module <b>74</b> may receive a signal from the MAF sensor <b>20</b> indicating a load on the engine. The knock control module <b>74</b>, however, may receive other signals indicating other engine operating parameters. The engine operating parameters (e.g., MAF) may be used to determine desired timings of the intake and exhaust valves <b>24</b>, <b>30</b> (i.e., periods that the intake and exhaust valves <b>24</b>, <b>30</b> are open or closed).

p-0034The knock control module <b>74</b> may adjust a period that the intake and/or exhaust valves <b>24</b>, <b>30</b> are open based on an intensity of the knock signal (the “measured engine knock”). In other words, when the measured engine knock increases, the knock control module <b>74</b> may decrease a load of the cylinder. Alternatively, however, the knock control module <b>74</b> may adjust the period that the intake and/or exhaust valves <b>24</b>, <b>30</b> are open when the measured engine knock was greater than a predetermined engine knock threshold during a previous engine cycle (i.e., when engine knock was detected). Decreasing the load of the cylinder may include decreasing a quantity of fresh air in the cylinder and/or diluting the air in the cylinder (e.g., with exhaust gas).

p-0035Thus, for example, the knock control module <b>74</b> may decrease a period that the intake valve <b>24</b> is open. Additionally or alternatively, for example, the knock control module <b>74</b> may increase a period that both the intake and exhaust valves <b>24</b>, <b>30</b> are open (i.e., increase valve overlap). Additionally or alternatively, for example, the knock control module <b>74</b> may decrease a period that the exhaust valve is open <b>30</b> (i.e., close the exhaust valve <b>30</b> earlier).

p-0036The valve control module <b>78</b> controls the intake and exhaust valves <b>24</b>, <b>30</b> based on the adjusted period(s) from the knock control module <b>74</b>. More specifically, the valve control module <b>78</b> may control the intake and exhaust valves <b>24</b>, <b>30</b> according to the adjusted period(s) using the hydraulic actuators <b>32</b>. For example, the valve control module <b>78</b> may generate a control signal for the hydraulic actuators <b>32</b>, and the hydraulic actuators <b>32</b> may then actuate the intake and/or exhaust valves <b>24</b>, <b>30</b> accordingly. Moreover, one intake valve <b>24</b>, one exhaust valve <b>32</b>, and one set (i.e., pair) of hydraulic actuators <b>32</b> are shown and discussed, the control module <b>50</b> may measure engine knock, adjust valve timing, and control valves of more than one of the plurality of cylinders <b>22</b>.

p-0037Referring now to <figref idrefs="DRAWINGS">FIG. 4</figref>, a method for controlling engine knock using EHVA begins at <b>100</b>. At <b>100</b>, the control module <b>50</b> may measure engine knock (e.g., via the knock signal from the engine knock sensor <b>48</b>). At <b>104</b>, the control module <b>50</b> may determine whether the measured engine knock is greater than a predetermined engine knock threshold. If true, control may proceed to <b>108</b>. If false, control may return to <b>100</b>.

p-0038At <b>108</b>, the control module <b>50</b> may adjust the period(s) that the intake and/or exhaust valves <b>24</b>, <b>30</b> are open based on the measured engine knock. At <b>112</b>, the control module <b>50</b> may control the intake and exhaust valves <b>24</b>, <b>30</b> based on the adjusted period(s) using the hydraulic actuators <b>32</b>. Control may then return to <b>100</b>.

p-0039The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification, and the following claims.